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1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.media;
18
19/**
20 * The AudioGain describes a gain controller. Gain controllers are exposed by
21 * audio ports when the gain is configurable at this port's input or output.
22 * Gain values are expressed in millibels.
23 * A gain controller has the following attributes:
24 * - mode: defines modes of operation or features
25 *    MODE_JOINT: all channel gains are controlled simultaneously
26 *    MODE_CHANNELS: each channel gain is controlled individually
27 *    MODE_RAMP: ramps can be applied when gain changes
28 * - channel mask: indicates for which channels the gain can be controlled
29 * - min value: minimum gain value in millibel
30 * - max value: maximum gain value in millibel
31 * - default value: gain value after reset in millibel
32 * - step value: granularity of gain control in millibel
33 * - min ramp duration: minimum ramp duration in milliseconds
34 * - max ramp duration: maximum ramp duration in milliseconds
35 *
36 * This object is always created by the framework and read only by applications.
37 * Applications get a list of AudioGainDescriptors from AudioPortDescriptor.gains() and can build a
38 * valid gain configuration from AudioGain.buildConfig()
39 * @hide
40 */
41public class AudioGain {
42
43    /**
44     * Bit of AudioGain.mode() field indicating that
45     * all channel gains are controlled simultaneously
46     */
47    public static final int MODE_JOINT = 1;
48    /**
49     * Bit of AudioGain.mode() field indicating that
50     * each channel gain is controlled individually
51     */
52    public static final int MODE_CHANNELS = 2;
53    /**
54     * Bit of AudioGain.mode() field indicating that
55     * ramps can be applied when gain changes. The type of ramp (linear, log etc...) is
56     * implementation specific.
57     */
58    public static final int MODE_RAMP = 4;
59
60    private final int mIndex;
61    private final int mMode;
62    private final int mChannelMask;
63    private final int mMinValue;
64    private final int mMaxValue;
65    private final int mDefaultValue;
66    private final int mStepValue;
67    private final int mRampDurationMinMs;
68    private final int mRampDurationMaxMs;
69
70    // The channel mask passed to the constructor is as specified in AudioFormat
71    // (e.g. AudioFormat.CHANNEL_OUT_STEREO)
72    AudioGain(int index, int mode, int channelMask,
73                        int minValue, int maxValue, int defaultValue, int stepValue,
74                        int rampDurationMinMs, int rampDurationMaxMs) {
75        mIndex = index;
76        mMode = mode;
77        mChannelMask = channelMask;
78        mMinValue = minValue;
79        mMaxValue = maxValue;
80        mDefaultValue = defaultValue;
81        mStepValue = stepValue;
82        mRampDurationMinMs = rampDurationMinMs;
83        mRampDurationMaxMs = rampDurationMaxMs;
84    }
85
86    /**
87     * Bit field indicating supported modes of operation
88     */
89    public int mode() {
90        return mMode;
91    }
92
93    /**
94     * Indicates for which channels the gain can be controlled
95     * (e.g. AudioFormat.CHANNEL_OUT_STEREO)
96     */
97    public int channelMask() {
98        return mChannelMask;
99    }
100
101    /**
102     * Minimum gain value in millibel
103     */
104    public int minValue() {
105        return mMinValue;
106    }
107
108    /**
109     * Maximum gain value in millibel
110     */
111    public int maxValue() {
112        return mMaxValue;
113    }
114
115    /**
116     * Default gain value in millibel
117     */
118    public int defaultValue() {
119        return mDefaultValue;
120    }
121
122    /**
123     * Granularity of gain control in millibel
124     */
125    public int stepValue() {
126        return mStepValue;
127    }
128
129    /**
130     * Minimum ramp duration in milliseconds
131     * 0 if MODE_RAMP not set
132     */
133    public int rampDurationMinMs() {
134        return mRampDurationMinMs;
135    }
136
137    /**
138     * Maximum ramp duration in milliseconds
139     * 0 if MODE_RAMP not set
140     */
141    public int rampDurationMaxMs() {
142        return mRampDurationMaxMs;
143    }
144
145    /**
146     * Build a valid gain configuration for this gain controller for use by
147     * AudioPortDescriptor.setGain()
148     * @param mode: desired mode of operation
149     * @param channelMask: channels of which the gain should be modified.
150     * @param values: gain values for each channels.
151     * @param rampDurationMs: ramp duration if mode MODE_RAMP is set.
152     * ignored if MODE_JOINT.
153     */
154    public AudioGainConfig buildConfig(int mode, int channelMask,
155                                       int[] values, int rampDurationMs) {
156        //TODO: check params here
157        return new AudioGainConfig(mIndex, this, mode, channelMask, values, rampDurationMs);
158    }
159}
160